Grepular

Exim 4 https://www.exim.org/ - Full featured, super light weight image

Radicale https://radicale.org/ (amd64+arm64)

A tiny image (amd64+arm64) containing just a statically compiled sqlite3 binary compressed using upx

https://www.parsemail.org

SpamAssassin 4 with automatic rule updates

SNI watcher for Email Privacy Tester

PowerDNS Watcher for Email Privacy Tester

A small image containing Apache's htpasswd